It is known to join two components having a hollow cross section by welding. In this context, the joining region between the two components is designed in such a way that an inside dimension of a first component participates in a press fit with an outside dimension of a second component. No gap is therefore provided in the joining region between the two components. It has now been found that problems occur at the weld seam if the two components do not have a clean surface. The components can have, for example, residues of lubricants, for example oil or naphtha, on the component surface. These residues are thus present in the joining region between the first and the second component. These residues then outgas upon welding and, for lack of any other possibility, escape through the weld bath. This causes the formation of pores in the weld seam which can assume, in particular, a tubular shape that can extend as far as the external surface of the weld seam. A leak can occur in the weld seam as a result; this is undesirable. The surfaces of the components to be welded must therefore be cleaned and free of residues before the welding operation.